This invention relates to methods and complexes for forming metal-containing films, such as metal or metal alloy films, particularly during the manufacture of semiconductor device structures. The complexes include a transition metal, particularly a Group VIIIB metal, and are particularly suitable for use in a chemical vapor deposition system.
The future of microelectronic devices will depend on new designs and new materials having superior properties. Metals like cobalt, and compounds like cobalt silicide, are useful candidates for use in memory devices. Cobalt silicide (CoSi2) shows advantages over the currently used tungsten silicide (WSi2) due to its lower polycrystalline film resistivity (about 15 xcexcxcexa9-cm for CoSi2 compared to about 70 xcexcxcexa9-cm for WSi2). Furthermore, CoSi2 shows good thermal and chemical stability.
In some applications, metal films are deposited using sputtering techniques; however, sputtered metal is not typically effective at filling contacts or vias because of shoulders or overhangs that form at the contact openings. These overhangs can lead to the formation of keyhole-shaped voids. Various collimation techniques help reduce this problem, but typically not enough to enable complete filling of very small geometries (e.g., less than about 0.5 xcexcm). Therefore, it is desirable to use chemical vapor deposition (CVD) to form metal and metal alloy films.
The desirability of CVD processes depend on the availability of suitable precursor complexes. Many precursor complexes are unsuitable because of their toxicity, pyrophoricity, poor volatility, and thermal instability. Thus, there is a continuing need for methods and precursor complexes for the deposition of metal films (including metal alloy films), on semiconductor structures, particularly using vapor deposition processes.
The present invention provides complexes and methods for forming metal-containing films, particularly transition metals (i.e., Groups IB through VIIIB, also referred to as Groups 3-12), on substrates, such as semiconductor substrates or substrate assemblies during the manufacture of semiconductor structures. The methods involve forming a metal-containing film using a transition metal complex. The metal-containing film can be used in various metallization layers, particularly in multilevel interconnects, in integrated circuit structures.
The metal-containing film can include a single transition metal, or a metal alloy containing a mixture of transition metals, or a transition metal and one or more metals or metalloids from other groups in the Periodic Chart, such as Si, Ge, Sn, Pb, Bi, etc. Furthermore, for certain preferred embodiments, the metal-containing film can be a carbide, nitride, phosphide, arsenide, stibnide, sulfide, selenide, telluride, or combinations thereof.
Thus, in the context of the present invention, the term xe2x80x9cmetal-containing filmxe2x80x9d includes, for example, relatively pure films of cobalt, rhodium, iridium, nickel, palladium, platinum, iron, ruthenium, and osmium, for example, alloys of these metals (or other transition metals) with or without other metals or metalloids (e.g., Si), or mixtures thereof. The term also includes complexes of metals or metal alloys with other elements (e.g., C, N, P, As, Sb, S, Se, and Te). The terms xe2x80x9csingle transition metal filmxe2x80x9d or xe2x80x9csingle metal filmxe2x80x9d refer to relatively pure films of single transition metals, for example. The terms xe2x80x9ctransition metal alloy filmxe2x80x9d or xe2x80x9cmetal alloy filmxe2x80x9d refer to films of the transition metals in alloys with or without other metals or metalloids, for example. That is, if there are no metals or metalloids from groups in the Periodic Chart other than transition metals, the alloy films contain combinations of the transition metals.
One preferred method of the present invention involves forming a film on a substrate, such as a semiconductor substrate or substrate assembly during the manufacture of a semiconductor structure, by: providing a substrate (preferably, a semiconductor substrate or substrate assembly); providing a precursor composition comprising one or more complexes of the formula: 
wherein: M is a transition metal (also referred to as metals of Groups IB through VIIIB or 3-12); each R group is independently H, a hydrocarbyl group, a halogenated hydrocarbyl group, a halide, or a silylated hydrocarbyl group, with the proviso that R3 and R4 are not both H (preferably, neither is H); each L group is independently H, a hydrocarbyl group, a halogenated hydrocarbyl group, a silylated hydrocarbyl group, or a halide; x=1 to 3; n=0 to 4; y=0 to 4; and forming a metal-containing film from the precursor composition on a surface of the substrate (preferably, the semiconductor substrate or substrate assembly). The metal-containing film can be a single transition metal film or a transition metal alloy film. Using such methods, the complexes of Formula I are converted in some manner (e.g., decomposed thermally) and deposited on a surface to form a metal-containing film. Thus, the film is not simply a film of the complex of Formula I.
Complexes of Formula I are neutral complexes and may be liquids or solids at room temperature. If they are solids, they are preferably sufficiently soluble in an organic solvent or have melting points below their decomposition temperatures such that they can be used in flash vaporization, bubbling, microdroplet formation techniques, etc., or combinations thereof. However, they may also be sufficiently volatile that they can be vaporized or sublimed from the solid state using known chemical vapor deposition techniques. Thus, the precursor compositions of the present invention can be in solid or liquid form. As used herein, xe2x80x9cliquidxe2x80x9d refers to a solution or a neat liquid (a liquid at room temperature or a solid at room temperature that melts at an elevated temperature). As used herein, a xe2x80x9csolutionxe2x80x9d does not require complete solubility of the solid; rather, the solution may have some undissolved material, preferably, however, there is a sufficient amount of the material that can be carried by the organic solvent into the vapor phase for chemical vapor deposition processing.
Yet another method of forming a metal-containing film on a substrate, such as a semiconductor substrate or substrate assembly during the manufacture of a semiconductor structure, involves: providing a substrate (preferably, a semiconductor substrate or substrate assembly); providing a precursor composition comprising one or more organic solvents and one or more precursor complexes of Formula I as defined above; vaporizing the precursor composition to form vaporized precursor composition; and directing the vaporized precursor composition toward the substrate to form a metal-containing film on a surface of the substrate. Herein, vaporized precursor composition includes vaporized molecules of precursor complexes of Formula I either alone or optionally with vaporized molecules of other compounds in the precursor composition, including solvent molecules, if used.
Preferred embodiments of the methods of the present invention involve the use of one or more chemical vapor deposition techniques, although this is not necessarily required. That is, for certain embodiments, sputtering, spin-on coating, etc., can be used.
Methods of the present invention are particularly well suited for forming films on a surface of a semiconductor substrate or substrate assembly, such as a silicon wafer, with or without layers or structures formed thereon, used in forming integrated circuits. It is to be understood that methods of the present invention are not limited to deposition on silicon wafers; rather, other types of wafers (e.g., gallium arsenide wafer, etc.) can be used as well. Also, methods of the present invention can be used in silicon-on-insulator technology. Furthermore, substrates other than semiconductor substrates or substrate assemblies can be used in methods of the present invention. These include, for example, fibers, wires, etc. If the substrate is a semiconductor substrate or substrate assembly, the films can be formed directly on the lowest semiconductor surface of the substrate, or they can be formed on any of a variety of the layers (i.e., surfaces) as in a patterned wafer, for example. Thus, the term xe2x80x9csemiconductor substratexe2x80x9d refers to the base semiconductor layer, e.g., the lowest layer of silicon material in a wafer or a silicon layer deposited on another material such as silicon on sapphire. The term xe2x80x9csemiconductor substrate assemblyxe2x80x9d refers to the semiconductor substrate having one or more layers or structures formed thereon.
A chemical vapor deposition system is also provided. The system includes a deposition chamber having a substrate positioned therein; a vessel containing a precursor composition comprising one or more complexes of Formula I as described above; and a source of an inert carrier gas for transferring the precursor composition to the chemical vapor deposition chamber.
The present invention further provides precursor compositions containing one or more complexes of Formula I wherein the compositions include at least two complexes containing different metals.